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Ancient limestone in Nevada and Montana preserves the chemical trail of that turning point in Earth\u2019s history.<\/p>\n
Reading those layers, Dr. Feifei Zhang at Nanjing University<\/a> found the same sharp lithium drop in both rock sections.<\/p>\n That fall moved in step with a major rise in carbon isotopes between 359 and 347 million years ago, tightening the timing of the transition.<\/p>\n Because the same pattern appears in two separate basins, the signal demands a broader explanation than any local geological quirk.<\/p>\n Why weathering matters<\/p>\n Rainwater slowly eats into fresh rock during silicate weathering<\/a>, a chemical process that locks carbon into dissolved material.<\/p>\n Rivers then carry that material to the sea, where it can end up buried in marine sediments.<\/p>\n When weathering speeds up over large areas, the atmosphere can lose carbon dioxide faster than volcanoes replace it.<\/p>\n That made the newly measured signal more than a curiosity, because it pointed to a direct route from rock breakup to cooling.<\/p>\n Lithium balance takes a plunge<\/p>\n Tiny changes in lithium isotopes<\/a>, the balance between two lithium forms, gave the team its clearest clue.<\/p>\n During rock weathering, lighter lithium tends to get trapped in new clay, while dissolved lithium keeps a different balance.<\/p>\n The researchers saw the lithium balance in seawater plunge by about 12 parts per thousand, a sign that continental weathering had intensified.<\/p>\n Older arguments had leaned on rougher clues, so this cleaner record gave the long-running debate firmer ground.<\/p>\n Checking the signal<\/p>\n Ancient rocks can mislead when later fluids or stray mineral grains overwrite the chemistry they first recorded.<\/p>\n To avoid that trap, the team screened the samples for contamination and compared two sections that formed in different settings.<\/p>\n Both sections showed the same broad swing, which made burial changes, hot fluids, and local mixing far less convincing.<\/p>\n That does not erase every uncertainty, but it leaves a global environmental jolt as the most plausible explanation.<\/p>\n Testing the weathering theory<\/p>\n Computer simulations then tested whether stronger weathering could actually drive the chain of changes seen in the rocks.<\/p>\n Those runs reproduced a roughly 30 percent rise in silicate weathering and a sharp fall in atmospheric carbon dioxide.<\/p>\n In the model, carbon dioxide dropped from about 1,000 parts per million to roughly 200, plus or minus 200.<\/p>\n That range would have pushed Earth much closer to the conditions needed for ice to build and persist.<\/p>\n Why did erosion speed up?<\/p>\n The study does not pin the trigger on one culprit, but it narrows the field to two strong ideas.<\/p>\n One involves rising mountain belts near the equator, where uplift would expose fresh rock and quicken erosion.<\/p>\n Another points to the spread of early seed plants<\/a>, whose roots and soils could have helped attack minerals.<\/p>\n Either path fits the data, and both would funnel more dissolved nutrients toward coastal seas.<\/p>\n Oceans lost oxygen<\/p>\n More nutrients in seawater<\/a> would not stay quiet, because marine microbes grow faster when phosphorus and other essentials rise.<\/p>\n As that growth expands, dead organic matter sinks and rots, using up oxygen in deeper water.<\/p>\n The models matched that story with stronger productivity and broader anoxia<\/a>, water deprived of usable oxygen, during cooling.<\/p>\n That link matters because it joins land chemistry to marine stress, not just to colder air.<\/p>\n A linked sequence of causes<\/p>\n For years, scientists argued over whether buried organic carbon or faster rock weathering did most of the cooling.<\/p>\n This study leaned hardest on weathering, yet it also showed how weathering could feed ocean productivity<\/a> and bury more carbon.<\/p>\n That combination helps explain why the carbon isotope jump was so large, and why older records<\/a> had already pointed to marked cooling.<\/p>\n Instead of picking one winner, the paper turns the old rivalry into a linked sequence of causes.<\/p>\n Lessons from the past<\/p>\n Natural weathering still removes carbon dioxide today, but it acts over spans far longer than human emissions.<\/p>\n \u201cThe past holds the clues to understanding the present and predicting the future,\u201d said Dr. Zhang.<\/p>\n That idea lands because climate models<\/a> need to know not only what removes carbon, but how slowly each pathway works.<\/p>\n No ancient process can cancel modern pollution on human timescales, though deep-time evidence can still sharpen long-range forecasts.<\/p>\n By tying one chemical trail in ancient seawater to rock breakdown on land, the study gives this climate reversal a workable mechanism.<\/p>\n Better records from other regions should test whether mountains, plants, or both pushed Earth across the threshold into ice.<\/p>\n The study is published in the journal National Science Review<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Faster rock weathering on land helped drive Earth\u2019s plunge into a deep ice age about 350 million years…\n","protected":false},"author":2,"featured_media":407244,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82],"class_list":{"0":"post-407243","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-ie","9":"tag-ireland","10":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/407243","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=407243"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/407243\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/407244"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=407243"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=407243"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=407243"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}